1. Field of the Invention
The present invention relates to a defroster construction for an automotive air conditioner.
2. Description of the Prior Art
A prior art defroster construction is shown in FIGS. 5 and 6. In the figures, 1 is a heater unit having inside thereof a heater core 2. 4 is a defroster nozzle main body having an opened connecting end 5 connected to a defroster side outlet 3 of the heater unit 1. The defroster nozzle main body 4 has bifurcated left and right front defroster nozzles 6 and 6 from which conditioned air is blown against a windshield 13. Between the front defroster nozzles 6 and 6 the defroster nozzle main body 4 is provided with a recessed portion 7 so as not to interfere with a bracket 15 for installation of an instrument panel 14. On the rear side or inboard side of the defroster nozzle main body 4 there are provided side ducts 8 and 8 which are integral with the defroster nozzle main body 4. The side ducts 8 and 8 are communicated with left and right side defroster nozzles 9, respectively. An air inlet 11 for the side ducts 8 and 8 is arranged centrally between the front defroster nozzles 6 and 6 and at the rear of an air inlet 10 for the front defroster nozzles 6 and 6 while being separately defined from the air inlet 10 such that a quantity of conditioned air supplied thereto from the defroster side outlet 3 of the heater unit 1 is distributed to the front defroster nozzles 6 and 6 and to the side ducts 8 and 8 under control of a defroster door 12.
Further, as shown in FIG. 7, it is known such a defroster construction in which air inlets 11 and 11 for the side ducts 8 and 8 are separately provided on the opposite sides of the air inlet 10 for the front defroster nozzles 6 and 6 so as to reduce the front to rear size of the defroster nozzle main body 4. A similar defroster construction is disclosed in Japanese Utility Model Provisional Publication No. 62-145766.
In the case of the construction of FIGS. 5 and 6, the defroster door 12 is adapted to define adjacent a rear part of the connecting end 5 a passage for allowing conditioned air from the heater unit 1 to flow into the defroster nozzle main body 4. Due to this, the ratio of a quantity of conditioned air to be supplied to the inlet 10 to a quantity of conditioned air to be supplied to the inlet 11 varies depending upon variation of opening of the defroster door 12, i.e., the ratio attained when the defroster door 12 is fully opened differs from that attained when partly opened. Particularly, when the defroster door 12 is partly opened, the quantity of conditioned air distributed to the air inlet 10 for the front defroster nozzles 6 and 6 is reduced relative to the quantity of conditioned air supplied to the air inlet 11 for the side ducts 8 and 8, thus making it impossible to defrost the windshield 13 desiredly or efficiently.
In the case of the construction of FIG. 7, the air inlets 11 and 11 are provided on the opposite sides of the inlet 10. Due to this, the air inlets 11 and 11 have a positional relationship of being upstream and downstream relative to the air flow "a" in the heater unit 1, thus causing the quantities of conditioned air supplied to the side ducts 8 and 8 to differ from each other and therefore causing the left and right front door window panels to be defrosted differently from each other.
Further, in either of the constructions, the recessed portion 7 provided between the front defroster nozzles 6 and 6 causes the flow of conditioned air supplied thereto through the air inlet 10 to deflect largely and blow out of the front defroster nozzles 6 and 6 as indicated by the arrows "a.sub.1 ", thus making it impossible to efficiently defrost the central portion of the windshield 13.